More and more wind turbines are being set up in locations that are windy but also hard to reach. That's making maintenance work increasingly challenging and expensive. The solution is to use remote monitoring and diagnostics based on smart data. Siemens is analyzing wind turbine operating data and using the information to develop target values. As a result, in many cases errors can be evaluated and corrected remotely.

Wind turbines are increasingly being installed in locations characterized by extreme climates so that they can exploit their high wind energy potential — on isolated mountain peaks, far offshore, or standing in snowbound desolation. “Such remote locations are ideal for wind power facilities. In addition to offering high wind energy yields, they don’t disturb any neighbors,” says Matthias Reichert, who supports the Cold Climate Version working group of the German Association of Machinery and Plant Manufacturers.

Offshore Turbines: A Tall Order for Maintenance Specialists

But regardless of how efficient extreme locations may be for electricity generation, they also make facility maintenance problematic. Bad or nonexistent infrastructure makes it more difficult to reach wind turbines, conduct maintenance work, and transport spare parts. Work is especially challenging at distant offshore locations, where weather and waves allow access only at limited times. In addition, large distances require well prepared service missions. So maintenance work is dependent on the vagaries of the climate and needs proactive planning. “That’s why remote monitoring and diagnostics is essential for reducing service intervals and for fully exploiting the advantages offered by offshore wind energy,” explains Merete Hoe.

Hoe knows what she is talking about, as she heads the diagnostic center of Siemens Wind Power Services in Brande, a village of 7,000 inhabitants in western Denmark. The facility, which is the company’s new remote monitoring and diagnostic center being inaugurated in September 2014, collects and evaluates all the operating data from more than 7,500 Siemens wind turbines all over the world.

Around-the-Clock Observation

This flood of data is tirelessly collected by the SCADA and Turbine Condition Monitoring (TCM) systems from Siemens. Whereas the SCADA system collects the turbines’ electronic and mechanical data as well as information about the weather and power grids, TCM is a vibration recognition system. Each wind turbine nacelle contains up to nine sensors that measure the vibrations of the turbines’ key components: the transmission case, the generator, and the main shaft bearing at the rotor blades. All Siemens wind turbines with an output of over two megawatts are equipped with TCM, which monitors them around the clock all year round.

After the vibration data is collected, it is transmitted to a reference database in Brande. The center automatically processes this data to create sample values for the normal operation of the various types of wind turbines. It continuously compares these target values with the current operating data of active turbines. The vibration sensors can detect even tiny deviations that indicate a defect. This enables the system to discover a damaged gear wheel, for example, long before the transmission breaks down. When needed, Siemens engineers can remotely switch off the affected wind turbine and send someone for repair work. Remote diagnostics is especially important for dealing with faults that develops slowly over time. In some cases, Siemens engineers can detect defective main shaft bearings a whole year before they have to be replaced. Thus the experts from Siemens can anticipate damage before it actually makes itself felt. The center measures more than 2,500 anomalies every week. The 100 analysts at the facility investigate these error messages and transmit more than 100 early warnings to the service technicians every week. If a case is serious, the technicians go directly to the affected wind turbine to take care of the matter after the center in Brande has provided them all of the information about the turbine and its operating history.

Smart Data to the Rescue

Huge amounts of data come together in Brande, which receives around 300 million measurement results every week. The facility continuously monitors 24 million different parameters, such as pressure, temperatures and vibration patterns. That translates into about 3,200 individual measurement values for each turbine, which have to be continuously collected and updated. In 2013, the database contained 97 terabytes of data – and that is expected to grow to 268 terabytes by 2015. “The remote monitoring and diagnostics of wind turbines is an excellent example of the use of smart data,” explains Hoe. In this case, smart data (the intelligent analysis of large amounts of data) reduces downtimes, lowers the number of expensive and time-consuming inspections that are needed, and consequently increases the wind turbines’ efficiency and energy output.

Approximately 3,200 operating parameters are monitored on each turbine.

Precision Diagnostics

The immense flood of extremely detailed data is the key to the system’s success because it enables diagnostics experts in Brande to precisely determine what kind of defect they are dealing with and whether or not a service team needs to be sent out to the affected turbine. For example, if individual turbine components exceed or drop below their temperature tolerance range, the wind turbine in question automatically shuts down. However, if employees in Brande come to the conclusion that the anomaly is not serious, they can remotely restart the wind turbine as soon as the temperatures have returned to their normal values.

The remote monitoring system’s performance data are impressive. “Our specialists can remotely solve 80 percent of the stopped turbines within ten minutes,” says Hoe. A further five percent of the problems take somewhat longer to solve, but do not require technicians to be sent to the defective turbines. In only 15 percent of the cases do service technicians actually have to go out and work on the affected wind turbines.

Pioneering Analytics

Siemens Wind Power Services has been using the advantages of smart data for quite some time. In 1998 Siemens became one of the first companies in the world to install sensors in its offshore and onshore wind turbines as standard procedure. These sensors have collected vibration measurements for more than 15 years now. “This pioneering achievement gives us a big lead in terms of the amount of data and experience we can draw on,” says Hoe.

Another advantage for Siemens is the fact that its wind turbines are distributed all over the world. “Because of this, we feed our database with operating data from a variety of turbine types and from different regions with varying operating conditions,” says Hoe. As a result, the company is continually expanding its range of sample values for normal operation.

Siemens technicians and local operators have around-the-clock online access to maintenance conditions at their facilities.

Of course, not only Siemens experts such as Hoe but also local wind turbine operators have access to their facilities’ data. They can monitor their wind turbines online at any time in order to stay up to date with the facilities’ operation and any maintenance work that is going on. Although remote monitoring and diagnostics reduces the frequency of service inspections, it is clear that a wind turbine is never truly alone, no matter how isolated it might be on land or at sea.